Mahdi army in control of Iraqi military HQ, military vehicle set on fire

What does the phrase 'Hello Sir' imply in a conversation?

In what contexts might someone use the greeting 'Hello Sir'?

How does the use of 'Sir' affect the tone of the greeting?

What cultural significance might the greeting 'Hello Sir' hold?

Can you provide an example of a situation where 'Hello Sir' would be an appropriate greeting?